Reference insertion device

ABSTRACT

A novel device in the general nature of an autofocus enlarger that is coupled to a projector/collimator, which is distinctive by virtue of its greatly expanded range of magnification, and its ability to dynamically produce a view of a target which continuously enlarges, thus to realistically depict a constant rate approach. The capabilities of our device are attained utilizing a macro lens having a range of magnification of from approximately 1/24th to 5 times the image source size, providing a variation in magnification of approximately 125 to 1 without physical inversion of the lens being necessary. This lens is arranged to be moved in a preestablished relationship to other components of our device such that a target scene or the like may be maintained in focus on a continuous basis throughout all changes in magnification, even though these be very rapid changes. In order that our machine could depict extreme ranges of magnification, we evolved a novel compound cam arrangement such that the table or plate upon which the macro lens is mounted is, quite desirably, caused to move very rapidly in accordance with classical lens formula requirements at a time near what may be regarded as the end of the run. Thus, the extremes of velocity required for a very realistic simulation of a range closure are made possible, amounting to a dynamic presentation that may, for example, be quite effectively utilized as a so-called missile exerciser, arranged to simulate an actual flight of a missile for the benefit of the tracker of such missile, or as a reference insertion device serving to dynamically project an aerial photograph or the like directly into the tracker.

United States Patent 11 1 Lakin et 21.

[ 1 June 24, 1975 l REFERENCE lNSERTlON DEVICE [75] Inventors: Charles T. Lakin, Winter Park;

William J. Leighty, Orlanda, both of Fla,

[73] Assignee: Martin Marietta Corporation,

Orlando, Fla.

[22] Filed: Nov. 16, 1972 [21] Appl, No.: 307,308

Related U.S. Application Data [63] Continuation-impart of Ser. No. 63, Jan, 2, 1970,

Primary ExaminerRichard E. Aegerter Aavismn! E.raminerA. .l. Mirabito A/mrney, Agent, or Firm-Julian C, Renfro; Gay Chin [57] ABSTRACT A novel device in the general nature of an autofocus enlarger that is coupled to a projector/collimator, which is distinctive by virtue of its greatly expanded range of magnification, and its ability to dynamically produce a view of a target which continuously en- Iarges, thus to realistically depict a constant rate approach. The capabilities of our device are attained utilizing a macro lens having a range of magnification of from approximately l/24th to 5 times the image source size, providing a variation in magnification of approximately 125 to 1 without physical inversion of the lens being necessary. This lens is arranged to be moved in a preestablished relationship to other components of our device such that a target scene or the like may be maintained in focus on a continuous basis throughout all changes in magnification, even though these be very rapid changes. lnorder that our machine could depict extreme ranges of magnification, we evolved a novel compound cam arrangement such that the table or plate upon which the macro lens is mounted is, quite desirably, caused to move very rapidly in accordance with classical lens formula requirements at a time near what may be regarded as the end of the run. Thus, the extremes of velocity required for a very realistic simulation of a range closure are made possible, amounting to a dynamic presentation that may, for example, be quite effectively utilized as a socalled missile exerciser, arranged to simulate an actual flight of a missile for the benefit of the tracker of such missile, or as a reference insertion device serving to dynamically project an aerial photograph or the like directly into the tracker.

24 Claims, 13 Drawing Figures PATENTEDJUN 24 ms SHEET FIG. 2

PATENTEDJUN24 I915 3.891. 314 SHEET 3 FIG. 3

FIG. 8

SHEET PATENTEDJUN 24 I975 1 REFERENCE INSERTION DEVICE RELATIONSHIP TO EARLIER INVENTIONS This is a continuation-in-part of our copending application entitled Reference Insertion Device, Ser. No. 63, filed Jan. 2, 1970 and now abandoned.

A device in accordance with the instant invention is capable of effectively serving as ground support equip ment in concert with a missile tracking system of the type taught in the allowed US. Pat. Application of Emrnons et al., entitled Prestored Area Correlation Tracker, Ser. No. 873,864, filed Nov. 4, I969, and assigned to the assignee of the present invention.

BACKGROUND OF INVENTION l. Field of Invention One embodiment of the present invention is directed toward ground support equipment of the type designed to optically transmit an aerial image of a predetermined target area to an optical tracker included in a tracking system mounted in a missile or other vehicle. The transmitted image is received by the optical tracker and stored as reference information in the form of a contrast pattern to control the course of the missile by comparison at a plurality of points of the prestored image with an actual view of the target area seen by the missile as it travels toward the point of impact. Testing capabilities are also included in the subject device, which is capable of projecting a continuous image of the target area to the prestored optical seeker in order to simulate the actual flight conditions experienced by the optical seeker, thereby insuring proper operation of the optical seeker in appropriately altering the course of the missile.

2. Description of Prior Art One utilization or embodiment of our invention is in conjunction with a missile having a tracker equipped with a prestored memory arrangement such that a plurality of related signals as a record indicative of the appearance of the area around a desired aim point can be memorized or stored and thereafter successively utilized in order to effectively provide progressively smaller area representations of the scene about the aim point. Such a tracker is descrived and claimed in the copending Prestored Area Correlation Tracker (PACT) application of Emmons et al., cited above.

An initial contrast pattern is stored for use at a specific point in the flight, by prestoring data produced by the instant device from a photograph or other representation of the target. Thereafter, at a succession of times during a range closure, additional contrast reference patterns are utilized to realign the tracker with the target. Between these realignments of the tracker, the tracker scanner operates to provide intermediate reference scans for aiming the tracker until the next prestored reference is used. Using either prestored references or intermediate references, memorized and live patterns are compared and correlation signals produced from which are derived control signals for use by the tracker.

The memory system of the missile tracker is preferably a rotating device operating synchronously with the scanning means, or any other suitable arrangement whereby the information stored therein is representative of the contrast pattern as a function of the scanner angle. The live and memorized patterns are correlated to provide information representative of the amount of angular misalignment between the two patterns. This information is further processed and roll, pitch and yaw control signals are generated for modifying the orientation of the optical axis of the tracker to minimize the angular misalignment between the current and memorized contrast patterns.

The tracker is electronically or mechanically gimballed within the missile to decouple the tracker from missile attitude motion. This permits three angular degrees of freedom for the optical axis thereof. Under such circumstances, the pitch and yaw signals (and in certain instances the roll signals) referred to above serve only to re-orient the tracker axis. Suitable sensors associated with the tracker serve to detect changes in tracker spatial orientation, which in turn are used by the missile autopilot to properly steer the missile to the target. A system such as described above is shown in assignees US. Pat. No. 3,372,890 by James R. Bogard et al, entitled Data Processor for Circular Scanning Tracking System," and in the assignees US. Pat. No. 3,416,752, to Clyde R. Hembree entitled Correlation Guidance System having Multiple Switchable Field of View."

An embodiment of the PACT invention with which our invention finds particular application is with the Distance Measuring Equipment embodiment (DME PACT), and is a terminal guidance scheme utilizing a prestored area correlation tracker (PACT) is addition to a DME transponder, both located in the missile airframe. The DME transponder is part of a triangulation mid-course guidance system which utilizes two ground stations and two loitering aircraft for the purpose of determining the real time position of the missile from the ground station baseline. The guidance error associated with the DME technique is small enough so that a correlator system with a single 20 field of view prestored reference would always find the actual target at the end of a DME midcourse guided flight.

The references that are prestored in the missile are generated by the use of the present RID device, which serves as a high magnification autofocus enlarger whose function it is to interpret a photographic plate on which has been placed a reconnaissance photograph, obtained by an actual flight. From this photograph, a plurality of references is made, which are to be used during range closure. Thus, the DME PACT system is designed to furnish a highly accurate terminal guidance function by converting such photographic data into four or more area correlator signatures, which are prestored in the missile.

As an example of the use of a DME missile that has been programmed by the use of our RID device, the launching aircraft takes off with the missile while keeping in contact with a spaced pair of ground stations with which the aircraft position can be triangulated. The aircraft flies toward the target but, depending upon the range of the missile, need not approach any closer than say 20 to 50 miles from the target.

In the typical instance, two loitering aircraft are utilized in concert with two ground stations, as previously memtioned, and these four elements are so arranged with electromagnetic equipment that the positions in terms of ground coordinates of the two loiter aircraft are known at all times. The two aircraft along with the missile and its transponder form a triangle. By means of the transponder in the missile, distance information from the missile to the two aircraft is determined and since the separation of the two aircraft is known, the missile location relative to the target can be determined by triangulation with relatively high accuracy. The autopilot in the missile can be directed by an electromagnetic link to correct its flight path so as to arrive not only at the correct target coordinates but to arrive at the correct target coordinates along a predetermined line of flight.

Upon nearing the target coordinates. the missile system is placed in a near vertical trajectory and as it approaches a predetermined altitude such as 10,000 feet. the first prestored picture is switched into operation and the correlator proceeds to track. The midcourse system previously discussed will always place the missile within the pull-in capability of the PACT. using a field of view. The prestored pattern was typically stored or memorized to correspond with what is actually seen by the missile in the 20 field of view as it passes through the 10,000 foot level. Just prior to reaching the 10,000 foot level, a radar altimeter located in the missile causes the PACT to switch to the 20 field of view and go into the track mode, using the first prestored reference which was prestored previously for use at a scaled range of 10,000 feet. As the missile passes through the 10000 foot level. a correlation peak detector measures the point where the live scene in the 20 field of view reaches the best match with the prestored reference. At this point, the system switches to the 4 field of view, and uses automatic rememorization until the radar altimeter indicates the altitude for using the next reference. When approaching for example the 5,000 foot level, the radar altimeter causes the system to switch out of the 4 field of view mode and into the 20 field of view tracking mode.

using the second prestored reference, which was scaled to match the actual scene as seen from 5,000 feet in the large field of view. As the point of best match is again detected, the PACT switches to the small field of view and again range closes, using automatic rememorization. Prior to reaching 2,500 foot level, the radar altimeter causes the system to switch to the third prestored reference and the track mode, using the large field of view. The correlation peak is again detected at 2,500 feet at which time the system goes back to the 4 field of view and tracks the target using automatic rememorization. Prior to reaching 1.250 feet, the radar altimeter calls up the fourth reference and causes the system to go into the track mode using the large field of view. If this is the last reference to be used. the automatic tracking from this point to the target determines the accuracy of the over-all system. Once the best match between the live data and prestored fourth reference is detected, the system goes into the 4 or small field of view and tracks all the way to the target. using automatic rememorization.

A preferred way of loading the prestored references for use in a DME missile is by the use of the Reference Insertion Device in which have been placed reconnaissance type photographs which are scaled and magnified by the instant RID so as to present to a scanning device for generating correlation signatures, a correct appearance of the target area at preselected altitudes. For example, the photograph may have been taken at 25,000 feet altitude. and by the use of the RID, a plurality of related references may be obtained concerning the target that will serve in the aforementioned manner to guide the missile to the target. The first reference could even be of a different altitude than that at which the reference was taken, and by way of example. could be scaled to apply to an initiation of terminal tracking via PACT at an altitude of 20.000 feet. The second reference in this example would be designed to be used at a slant range of say 10.000 feet. with the remaining references being used each time an additional 50 percent range closure takes place.

SUMMARY OF THIS INVENTION In accordance with this invention we have provided a novel device in the general nature ofan auto enlarger. distinctive from ordinary. state-of-the-art auto enlargers, in that it has an expanded range of magnification.

Perhaps even more importantly. our novel device is specifically designed to produce a view of a target which continuously enlarges so as to appear to be approaching at a constant rate. Moreover. the simulated speed of approach of the target is directly proportional to the speed of the drive motor, which speed can be easily varied at the behest of the viewer. Our device is capable of high speed dynamic operation. which of course is in stark contrast with prior art auto enlargers. which were used for static applications.

The capabilities of our device are attained utilizing a macro lens having a range of magnification of from approximately 1/25 to 5 times the image source size. giving us an image factor of approximately to l without physical inversion of the lens being necessary. This lens is arranged to be moved in a pre-established rela tionship to other components of our device such that a target scene or the like may be maintained in focus on a continuous basis throughout all changes in magnification, even though these be very rapid changes.

Although other machines have already been built utilizing at least some of the basic principles herein involved, all known machines having large magnification factors have been bulky and unwieldy. requiring large image sources, several feet in size. and creating considerable problems in lighting. Our system is unique. for by use of novel compound cams taught herein, it is pos sible to obtain a very wide magnification range, accomplished in a machine of compact size. Standard photographic plates may be used as image sources. and an ordinary size light source utilized.

Our unique compound cam arrangement preferably involves the use of one or more pairs of coaxial cams arranged to turn relatedly. and to provide suitable motion to the support means for the macro lens. One embodiment of our invention involves a first pair of cams, turning comparatively slowly, with cam followers or fingers adapted to follow a spiral groove cut in the face of each cam. When range closure is being depicted, the follower disposed in the groove of the cams takes motion from the cams and brings about a comparatively small but ever increasing motion of the macro lens with respect to a fixed position of the projected image.

Although it was desired that our machine depict extreme ranges of magnification. we found that it was not possible to cut a single cam that could provide the needed motion to the macro lens. Therefore. we evolved a compound cam arrangement wherein each first or inner cam is associated with a second or outer cam whose active portion or face is in the same plane as the face of the smaller cam. with a groove of preestablished configuration or rise being cut in such face. In other words, the active faces of the two cams are designed to be coplanar, with the same cam follower being designed to pass from the groove of the inner cam to the groove of the outer cam of each pair at a pre-established location. By virtue of the outer cam rotating at a higher speed, the slope of its groove can be 4 reduced to a practical value. As a result of the proper relative contouring of the cam grooves, the table or plate upon which the macro lens is mounted is, quite desirably, caused to move quite rapidly in accordance with classical lens formula requirements at a time near what may be regarded as the end of the run. Ideally, actual maximum slope on both cams is approximately equal.

This is to say, the slope of the groove of the large cams is such as to physically move the lens table at the desired rate and extent necessary to properly simulate the range closure. Thus, it is to be seen that by the use of our unique cam arrangement, the extremes of velocity required for a very realistic simulation of a range closure is made possible, amounting to a dynamic presentation that can be quite effectively utilized as a socalled missile exerciser, arranged to simulate an actual flight of a missile for the benefit of a tracker of such missile.

Used as a Reference Insertion Device, our machine is arranged to receive an aerial photograph or the like and to dynamically project such photograph at an extremely wide range of magnifications. Such projection can be made from our machine directly into the tracker of a missile. as set forth hereinbefore.

Another aspect ofthe subject invention is directed to a projection assembly for projecting the image of the target area into the optical seeker portion of the missile tracking system both for the purpose of storing refer enee information within the tracking system and for testing the operation of the tracking system and associated optical seeker throughout an entire simulated approach to the target. Thus, the testing procedure is accomplished by comparison of the prestored reference information with a simulation of the target area as would be viewed by the optical seeker during actual flight. This series to simulate the entire view actually to be observed by the optical seeker as it travels over the target area within the predetermined alitude range. Operation of the tracking system during its comparison of the reference image with the simulate flight serves to insure proper operation during actual flight.

As should now be apparent, it is a primary object of our invention to provide an auto enlarger ofa vastly improved type in which a drive arrangement, operating at a selected constant speed, can be used to generate a continuously varying magnification of a given scene so as to effectively simulate a constant velocity range closure.

It is another object of our invention to provide an auto enlarger ofthe compact size and economical construction, having a greatly expanded range of magnification.

It is still another object ofour invention to provide an auto enlarger specifically designed for high speed dynamic presentations, such that a range closure representative ofhigh speed travel from a high altitude down to ground level can be portrayed in an effective, highly realistic manner.

It is yet another object of our invention to provide a device eminently suited for use with missile applications, such that socalled missile exercises can be conducted for tracker checkout, and so that a related se ries of representations of a selected target can be rapidly placed in the tracker memory for subsequent use against the target.

It is yet still another object of our invention to provide an novel compound cam arrangement capable of providing an extremely wide range of motion to a macro lens utilized in the projection of an optical representation of a target area or the like, with such cam arrangement being operated in timed relation with means utilized for maintaining the optical source in the proper optical relationship to the macros lens through out its range of movement.

These and other objects, features, and advantages will be more apparent from a study of the appended drawings in which:

FIG. 1 is a perspective view of our Reference Insertion Device, with certain portions cut away to reveal internal construction,

FIG. 2 is a side elevational view of an idealized version of the principal optical components of our device, with certain structural portions being in section;

FIG, 3 is a fragmentary perspective view of the drive portions of our device associated with maintaining the macro lens and the image source in the proper opertive relationships, with certain aspects of construction being omitted for reasons of clarity;

FIG. 4 is a side elevational view of one of the large cams utilized in conjunction with our invention;

FIG. 5 is a cross-sectional view of the cam of FIG. 4, revealing certain important countour thereof;

FIG. 6 is a side elevational view of one of the small cams;

FIG. 7 is a cross-sectional view of the small cam of FIG. 6, with it being obvious from this figure and from FIG. 5 how a given pair of cams can be nested together with their active faces in coplanar relationship;

FIG. 8 is a view of the large and small cams in assembled relationship, with their respective grooves in a concurrent position in which a cam follower would be partially in both grooves.

FIG. 9a is a schematic representation of maximum demagnification, in which the image source is at the maximum displacement from the macro lens, typical of the relationship of these components at the start of a run, when the distance to the target is greatest;

FIG. 9b is a schematic representation of the optical relationships when the components shown in FIG. 9a have moved to such a position that the image and object sizes are equal;

FIG. 9c is a schematic representation of the same components, in which the demagnification has been reduced, such that the total object size is smaller than the image size, and the magnification of the selected target is therefore largest, thus representing the closest approach to the target;

FIG. 10 is an illustration of the idealized portion of a viewing device when being utilized with the optical components of our device; and

FIG. 11 is a graphical representation of the motions of the macro lens and the image source.

DETAILED DESCRIPTION Turning now to the figures of drawing, it will be seen that a Reference Insertion Device 10 in accordance with a preferred embodiment of our invention is shown in FIG. 1, which figure may be regarded as illustrating the device in its fully assembled, operative form. Our Reference Insertion Device. which may hereinafter be referred to as RID, includes a metallic support frame 12, at the lower portion of which a base plate 14 is utilized. Upon this base plate a number of components associated with this invention are mounted.

Because there will be occasion from time to time to move a RID to a different location, we provide a pair of handles I6 on opposite sides of the device, thus to simplify the task of two persons lifting the device into an automobile or onto a dolly or truck for transport to another location. Safety plates or covers 18 are attached to each side of the frame by threaded fasteners 20 or the like, with these plates serving to protect the operators from the moving elements of the RID drive assembly, and to prevent the entry of extraneous matter into the mechanism.

Several of the optical elements of our invention are illustrated in FIG. 1, but the interrelationships of these elements are better observed in FIG. 2. These optical elements include a first or lower obervation lens 22, disposed in a lens mounting member 23 whose weight is borne by the base plate I4. The lens 22 is mounted so as to be in proper optical relationship with a second or upper obervation lens 24. FIG. 2 also illustrates a macro lens that is mounted in vertical alignment with other components of our device, for vertical movement with respect to support frame 12. Inasmuch as lens 25 must provide a large range of magnification, a high quality lens must be used, and for example we prefer to use a Canon FL 55 mm. F/I.2 lens produced by the Canon Company of Tokyo, Japan. Such a lens has the extremely advantageous capability of magnification in both the microscopic and telescopic range without physical inversion of the lens being necessary. We have found that a RID device using such a macro lens is able to obtain a magnification range of to I quite easily, but can also go to a range of more than 120 to I.

In this preferred embodiment of our invention, the macro lens 25 is disposed for vertical movement in alignment with image source mounting means 30, upon which the image source 29 may be mounted. The image source may for example be in the form of a photographic transparency of the scene to be dealt with, but for reasons of clarity, is depicted here as an arrow. FIG. 2 reveals optic axis 27, which may be regarded as passing through the centers of the image source, the macro lens 25, and thence through a beam splitter. This beam splitter may be in the form of a semitransparent pellicle 104 angularly mounted with respect to both the optic axis 27, and an axis extending between lens 24 and 94. This latter arrangement will be discussed at length hereinafter.

Thereafter, the optic axis 27 may be regarded as passing through the center of objective lens 120 located below the pellicle 104 in the mounting member 23. A reflecting means 118 is angularly positioned in a lower portion of the lens mounting member 23 in such a relationship to the optic axis 27 as to extend the optical path regarded as originating with the image source and passing through the lenses 25 and I20, on around through the field lens I I6, the rotatably adjustable reticle 110, the field lens 114 and thence to the first obervation lens 22.

Both of the principal moving components, macro lens 25 and image source 29, must move along the optic axis 27 or else the person viewing the changing scene through lens 22 will become aware of drift away from the reticle IIO. Accordingly. we utilize an attachment plate 31 for supporting the image source mounting means 30, with precision adjustment means being employed on the plate 31 so that the mounting means 30 may be selectively moved with respect thereto until such time as the center of the scene represented by the image source 29 is disposed on the optic axis 27.

Reference to FIG. I reveals the use of adjustment means in the form of a graduated micrometer dial 32 and graduated adjustment dials 34 and 36, which are used to position the image source 29 along the equivalent of the pitch, roll and yaw axes respectively. This adjustment through operation of the adjusting means 32, 34 and 36 thus serves to physically move the transparency or image sorce mounting means 30 with respect to attachment plate 31 so as to align the image source 29 with other alignment means associated with the RID, in a manner and for a purpose which will be set forth in greater detail hereinafterv A light source 40 mounted in cooperative relationship with a light condenser 42 is utilized to direct light through the scene 29 and through the macro lens 25 and the pellicie 104, with the latter resulting in the formation of visual images 106 and 108, as shown in FIG. 2. More precisely, image 106 is formed by the projec tion of image source 20 through macro lens 25 and onto pellicle 104 where it is reflected to the position of image 106 adjacent collimating lens 94. Similarly. image I08 is formed by the image source 29 being projected onto pellicle I04 and being transmitted through pellicle I04 to the position shown. Both images I06 and 108 are thus established at a selected fixed position and have a fixed predetermined size dependent upon the focal point of the collimating lens 94. The magnification of the imagery within this predetermined size and position is accomplished as a function of the synchronized motion of two pairs of cams I44 and 146, and a pair of threaded screw devices 128, described in detail hereinafter, which serve to precisely position macro lens 25 and the image source 29, respectively. The function of images 106 and I08 will later be explained with reference to the alignment assembly and the information transmission procedure of the RID.

As seen in FIG. 2, the macro lens 25 is mounted upon support plate 26, and inasmuch as this plate is subjected to considerable vertical motion as a result of the operation of the cams shown in FIGS. 3 thourgh 8, a cross-bar 28 is utilized on the front of plate 26, as shown in FIGS. I and 3, in order to provide desirable stiffness to the plate.

In FIG. I is illustrated a cam follower finger 156, mounted on plate 26 and arranged, as shown in FIG. 3, to reside on occasion in groove 158 of rotary cam 144, with the cam rotation providing substantial vertical motion to plate 26. As a matter of fact, a pair of the rotary cams is used on each side of our device, these being inner cam 146 and outer cam 144; see FIG. 8 in particular. Each outer cam turns in the same rotative direction as the respective inner cam, but turns in an entirely different rate of rotation, typically many times as fast. This arrangement makes it possible for the plate 26 and its lens 25 to undertake vertical motion at an everchanging rate. first very slow, with smooth transistion to very fast, with such an arrangement being necessary in order to obtain the requisite range of magnification of the scene.

Vertical alignment between certain of the vertically movable members is assured by the utilization of a pair of vertical shafts 56 as shown in FIG. 1, only one of which is to be seen in FIG. 3. These shafts are of substantial construction, serving as both supports and guide elements. Shafts 56 are firmly fixed to the frame 12 of the RID, so that they will not move during the time that the macro lens plate 26 is caused by cam rotation to move vertically, and are utilized on opposite sides of the device to assure symmetry and to prevent binding. Linear bearings such as 54 and 57 may be fixed to light source mounting frame 44 and to attachment plate 31, respectively, at the locations where these members contact the shafts 56, thus to assure smooth movement of these members along the shafts.

Although it would otherwise be desirable for the guide means 56 to be in contact with each of the vertically movable members or plates in order to extend stability thereto, we found that when the attachment plate 31 is caused to closely approach the support plate 26, which normally occurs near the end of a range closure simulation, the linear bearings or bushings 57 tended to come into contact with the plate 26, which of course is undesirable. Accordingly, it was necessary to configure the portions of plate 26 in thhe vicinity of the shafts 56 so as to avoid contact with the shafts; note FIG. 3.

In order that the light source 40 will be enabled to provide a uniform amount of illumination to the macro lens 25 through all changes of lens location, we make constant the distance between the light source mounting frame 44 and the macro lens support plate 26. This is accomplished by the use of two or more support shafts 58, that are affixed to both the frame 44 and the plate 26. Thus, as the fingers 156 provide motion to lens plate 26 by following the cam grooves, they also bring about identical motion of the source of illumination as well.

The vertically movable support shafts 58 are utilized to perform a stabilizing function as well, for in accordance with the arrangment best shown in FIG. 3, a pair of linear bearings 62 and 62a is provided on each side of the machine, in which the respective shafts 58 are slidable. These linear bearings are rigidly attached to the frame 12, and effectively provide the requisite stability to the plate 26 during vertical movements thereof.

Whereas motion at an ever changing rate takes place between the macro lens support plate 26 and the image position 106, an essentially uniform motion must take place, for lens geometry reasons,s between the mounting plate 26, and the plate 31 upon which the image source 29 is mounted. This uniform motion is brought about in accordance with this invention by the utilization of a pair of vertically disposed, simultaneously rotatable shafts 128; see FIG. 1. The upper portions of shafts 128 are equipped with threads 130, as depicted in FIGS. 2 and 3. The threaded portion of each shaft 128 threadedly engages the plate 31 in order that height changes of that plate can be brought about in response to the uniform rotation of the shafts 128.

The shafts 128 are rotationally mounted between the plates 26 and 44, with bushings 136 being utilized in these plates so that the threaded portions 130 of the shafts can be rotationally free, but axially fixed in plates 26 and 44. A splined portion 134 is utilized in the lower part of each shaft 128, with each of these splined portions being slidably disposeod in a respective bevel gear 136. Rotative power from electric motor 68 (FIG. I) is supplied to the bevel gear 138 shown in FIG. 3 by means ofa shaft 140 turning a bevel gear 142 arranged to mesh with gear 138. It will be recalled that rotation of the cams causes considerable vertical motion of the plates 26 and 44, but the gears 138 and 142 (as well as the other pair of bevel gears not illustrated) remain in mesh inasmuch as the splined portions 134 of the shafts 128 slide inside the gears 138 to whatever extent is required by the motion of the plates 26 and 44, and vertical movement of the gears is neither required nor desirable.

Lamp box 38, as shown in FIG. 1, houses the light source 40 and light condenser 42 depicted in FIG. 2, which arrangement serves to direct light through the transparency 29 on image source mounting means 30 and thence upon the lens 25, as previously mentioned. This illumination arrangement serves to backlight the image source 29 in order to optically project the image source through the lens 25. Further structural details of the lamp box 38 in addition to the mounting frame 44 include a vent construction 46 to remove heat from within the lamp box 38 created by lamp 40, and light intensity control knob 48, each of which is depicted in FIG. 1. A power meter 50, used as a reference for light intensity, and ON-OFF switch 52 are also provided on lamp box 38.

The lamp box 38 thus is primarily supported in a fixed spaced relation to macro lens 25 by means of the support shafts 58, with vertical movement of the macro lens 25 relative to the RID frame 12 brought about by cam rotation causing the same vertical movement of lamp box 38. In this manner, a fixed distance relationship is maintained, with lens 25 at the vertex of the cone of illumination established by light condenser 42. An optimum and constant distribution of light flux to the lens 25 is effected by focusing the image of lamp 40 on the aperture or iris of lens 25.

counterweight assemblies 64 are mounted upon vertically disposed crossbars 13 of RID frame 12 and these serve to principally support the weight of the macro lens support plate 26 and the vertically movable components mounted thereon. A tension band 66 is operatively disposed in each of the counterweight assemblies, with the lower end of each tension band being affixed to its respective side of the plate 26. As will be obvious, the tension bands 66 (only one of which is shown in FIG. 1) retract into their respepctive assemblies 64 upon upward movement of plate 26, and are extended by the downward movement of this plate, while at all times maintaining an upward, gravity compensating biasing force thereon. Inasmuch as the mounting frame 44 is supported by the plate 26 by virtue of the support shafts 58, and inasmuch as attachment plate 31 is also supported by plate 26 by virtue of its relationship to the threaded screw devices 128 that are borne by plate 26, it may be properly said that the counterwieght devices 64 provide a gravity compensating bias on all of the principal, linearly-movable parts. However, the counterweight devices do not assert an upward force precisely equal to the weight of these principal, linearly movable components. Rather, we prefer for there to remain a comparatively small downward bias of say 10 to 20 pounds, so that the fingers 156 will ride only on one side of each groove of the cams, thus avoiding a problem involving backlash.

It should be pointed out that there is no firm requirement that the plates 26 and 31 and mounting frame 44 move vertically, although the vertically movable relationship described in accordance with this embodiment makes more convenient the handling of the image source 29 than would otherwise be the case. As an example an alternate embodiment, the arrangement could be such that our RID device utilizes components that move horizontally, and in the latter instance, the use of the counterweight assemblies 64 would of course not be required.

A limit switch actuator rod 67 is provided, as shown in FIG. 1, in order to prevent jamming of the moving components by the action of the threaded screw members and the travel of the cams. The rod 67 moves vertically with limited travel between support plate26 and mounting frame 44 and serves to operate a pair of spring loaded switches (not shown) through adjustable stops on each side of attachment plate 31. These switches are physically located in limit switch box 69 visible in FIG. I, and are electrically disposed in the circuit of drive motor 68 so as to prevent its further operation at such time as plate 31 closely approaches the plate 26 (during a range closure simulation), or when plate 31 closely approaches mounting frame 44 supporting the lamp house (during the resetting of the machine.)

The driving assembly of the present invention will be described in greater detail later, but it should be briefly mentioned that the motor 68, as shown in FIG. 1, is mounted on base plate 14. This is a reversible, variable speed electric motor arranged to supply power to drive belt 70 to drive a plurality of gear elements mounted within gear casings 72 and 73. Drive shafts 140, depicted in FIG. 3, extends from gear casing 73. The operation of the driving assembly and its functional relationship to the movement of various related parts will later be described with specific reference to FIGS. 3 through 8.

In addition to the above, other components of the RID as disclosed in FIG. 1 include a control box 74 having suitable knobs for direction and speed control, an on-off switch 78, and indicating lamp 80. Electrical cord 82 supplies a source of electric power to the RID operation of the motor 68 and the many controls and components of our device. The capacitors 84 and 86 are filters on the rectified direct current supplied to the lamp 40, thus to provide flickerless illumination, permitting operation of the cooperating missle tracking system in a simulated flight.

It is well known that the light intensity output of a magnifying system of the general type shown herein will change as magnification changes, and accordingly it is necessary to selectively increase the effective illumination provided from the bulb 40 as the macro lens moves. For example, in a typical instance involving the simulation of a range closure situation, the cams would be continuously lifting the support plates 26, but at an ever-changing rate, whereas the shafts 128 will be rotating in such a direction as to be simultaneously bringing the image source 29 closer to the macro lens, proceeding at a constant rate. Near the end of a typical run, the image source is actually being moved upwardly, due to the fingers 156 being in the steeply sloped portions of the outer cams, although in reality,

the image source is at all times being moved ever closer to the macro lens 25 by the shafts 128. In order to maintain a constant intensity of light output from the RID, such as to a nearby missle 96, any of three different types oflight modulation schemes could be utilized. (1) For example, the voltage applied to the bulb 40 could be selectively increased as the macro lens 25 is raised during the depicting of a typical range closure. However, the color of the lamp would also change; (2) The effective diameter of the macro lens 25 may be increased by appropriate adjustment of the iris in macro lens 25. This could be accomplished in accordance with one aspect ofour invention by the use ofa cam 71, whose active surface is contacted by a cam follower note FIG. 1; or (3) A variable density filter can be caused to change in density as the macro lens 25 is raised. Procedure l above is usually undesirable, procedure (2) is practical, but procedure (3) is considered most desirable since the lens sizes and therefore lens effects on image quality have been varied the least by the utilization of a filter, such as shown at 43 in FIG. 2.

We prefer to use a 2,000 watt bulb 40 operated at full power level. The variable density filter 43 may, for example, be a variable density wedge filter of the type manufactured by Eastman Kodak Company, involving the use of a pair of relatively movable filter members. Such movements of the filter members changes the density of the filter and accordingly the effective light output of our device, such as to a missle 96. We prefer to arrange the filter members to be moved non-linearly in the density-changing relationship in response to rotativc movements of the shafts I28.

Bellows 88, and 92 are provided in order to channel the illumination along, and shield stray illumination from, the optical path defined by light source 40, image source 29 and macro lens 25. As generally represented in FIG. 2, bellows 88 extends between mounting frame 44 and bellows lifting assembly 37 associated with attachment plate 31; bellows 90 extends between plate 31 and plate 26', and bellows 92 extends between plate 26 and the upper portion of mounting member 23. The bellows lifting assembly 37, visible in FIGS. 1 and 2, enables the lower portion of bellows 88 to be lifted away from plate 31, and then latched to the underside of plate or frame 44, thus affording access to the image source 29. In this way, a rapid change from one scene to another can be effected. Also, for convenience, we preferably construct the lamp box 38 and mounting frame 44 to hinge so that the light source 40 can on occasion be swung rearwardly, thus to be clear of image source 29, for ever better access. A latch 60 is utilized to prevent undesired tilting of the lamp box and frame.

The RID optics as represented in FIG. 2 further include a projection assembly comprising the projection lens 94 mounted on the RID relative to its exterior such that the missile 96 may be positioned in optical alignment with lens 94 for transmission of optical reference information to the target tracking system of the missile. More specifically, missile 96 has mounted therein a tracking system which includes an optical tracker generally indicated at 97 having a receiving lens 98, optical tracker focal plane 100 and alignment means 102. A tracking system of this type is more fully described in the allowed application of Emmons et al referenced above, and per se forms no part of this invention. The method of alignment between the RID l0 and the optical tracker portion 97 of the tracking system of the missile 96 will be explained in detail hereinafter.

FIG. 2 further discloses the optical elements compris ing the alignment assembly of the RID which is utilized to efficiently and accurately align the image source 29 with the optical scanner 97. The alignment assembly includes the aforementioned first or lower observation lens 22 located on the mounting member 23 adjacent to an adjustably mounted reticle 110.

Markings on reticle 110 are two lines crossing at 90 to form a a! the center of the reticle. This is permanently aligned so as to indicate the optical center at all positions ofthe macro lens 25 and the image source 29. A movement of adjustment of the image source 29 in the two sidewise directions (that is, the two directions perpendicular to the optical centerline defined by the line drawn from lamp 40 through the center of lens 25) is usually necessary to select the proper target in the image source 29. The two (X, Y) movements can be accomplished by shifting the image source 20 in the image source mount 30, this being brought about by appropriately manipulating graduated micrometer dial 32, which moves the image source 29 in the direction equivalent to missile pitch changes, and by appropriately manipulating the graduated adjustment dial 36, which moves the image source 29 in the direction equivalent to missile yaw changes. This being accomplished, it can be considered that the selected target in the image source 29 has been properly align to the RID 10 in the pitch and azimuth dimensions.

The roll alignment of the RID 10 as well as the pitch, yaw and roll alignment of the optical tracker 97 of the missile 96 is accomplised after the optical tracker system 97 is placed before the projection lens 94. For this adjustment. the backlight lamp 124 and backlight diffuser 126 are placed over lens 22 and illuminated. These items are preferably in the form of a single unit 127 that fits over this lens, much like an oversize lens cap. By viewing through observation lens 24 will be the alignment means 102 of the missile tracking system, the center of which indicates proper centering of imagery for the optical tracker 97. A tracking system of this type is more fully described in the above-referenced application of Emmons et a]; and per se forms no part of the instant invention. Either the missile 96 or RID 10 may be moved in actual pitch and yaw directions until the image of the alignment means 102 is superimposed precisely on the image of the center of recticle 110 as seen through lens 24, at which time the optical tracker 97 may quite correctly be regarded as aligned in pitch and yaw to the RID l0. Inasmuch as the selected target in the image source 29 had previously been aligned to the RID 10 in the directions equivalent to pitch and yaw directions, the target image on the image source 29 has now been aligned in pitch and yaw with the optical tracker 97.

The next step in alignment is to pitch the optical tracker 97 by its internal control system. The image of the alignment means 102 will be seen moving in an upand-down direction as seen through lens 24. Now the image of reticle 110, backlighted by the light from lamp 124 through diffuser 126 on lens 22 is also visible through lens 24. The recticle 110 is rotated by lever [12 (FIG. 1 until the image of the vertical line to the reticle l 10 is on the image of the path of the alignment means 102 as it is pitched upwards and downwards. This step establishes the optical tracker 97 roll axis to be in alignment with a roll axis as defined by the line in reticle 110.

The final step in alignment is to align to the rotation of the image source 29 about its target point with that of the line in reticle 110. The lamp and diffuser unit 127 is removed from lens 22. Viewing through lens 22, the image of the image source 29 is seen superimposed on reticle 110. The image source 29 is then rotated by graduated roll adjustment dial 34 until the roll coordinate origin for the desired simulated path over the target are) is aligned with the line in reticle 110. The image source 29 and optical tracker 97 are at this point properly aligned in all directions (pitch, yaw, and roll).

As mentioned above. visual images 106 and 108 are positioned at fixed locations in mounting member 23. In addition. these images are formed at various magnifications of image source 29, which is dependent on the position of image source 29 and macro lens 25 and their combined position, as a unit, relative to the fixed positions of images 106 and 108. Consequently, a drive assembly of the type already described is provided to efficiently and accurately position these elements in their desired locations and further to move these elements relative to one another at a desired predetermined rate. More specifically, FIG. 3 shows the support plate 26 for macro lens 25 being movably mounted a spaced distance from support plate 31 by a drive means including the drive shaft 126.

As the pair of shafts 128 rotates support plate 26 is maintained in a fixed vertical position relative to shafts 128 due to busing 136 being axially fixed but rotationally movable relative to the shafts, as explained before. However, the threaded portion engages image source support plate 31 in threaded, nut and bolt fash ion, such that rotation of shafts 128 causes vertical movement of plate 31 relative to plate 26. In addition, this relative movement may occur in either an up or down direction, and at a uniform rate dependent upon the direction of rotation and speed of the motor 68.

As previously mentioned, motor 68 is a variable speed motor serving to drive the various mechanisms associated with our invention. We prefer to use a variable speed DC motor, associated from which is a control box 74, as shown in FIG. 1. This control box has a directional control knob 76a and a speed control knob 76b. Although we are not limited to such, we prefer to use a Bodine Model 280 motor, which is a direct drive motor of Va horsepower, producing shaft outputs in the speed range of 60 to 2,400 rpm. Alternatively, we may use a A horsepower motor having similar characteristics to the above. Used with this motor we prefer a Bodine 500 series speed control such as a Model 906. type ASH 500. The characteristics of this type arrange ment are such that the output of motor 68 will be uniform at any selected speed within the capability of the device, with any aberration in speed being very small. By manipulation of the knob 70b of the control box, the speed at which a range closure is reproduced can be changed from run to run, if such is desired, or even the 'speed can be changed during a run.

The motor 68 turns a pulley that drives belt 70, which belt in turn drives a pulley on shaft 140 on the gearbox used. Actually, the gearbox is in two halves, 72 and 73, as seen in FIG. I, with the shaft 140 extending into each half. On each end of the shaft 140 is disposed a gear 142, with FIG. 3 showing only two of these. As previously mentioned, each bevel gear 142 turns a respective bevel gear 138 that in turn causes rotation of its shaft 128.

Shaft 140 also causes the rotation of a pinion (not shown) which is in mesh with a gear which, through a multistage reduction (also not shown causes the rotation of shaft 148. Affixed to the shaft 148 are a pair of gears 152, only one of which is shown in FIG. 3. Each gear 152 is coupled to a respective gear 154 through a multistage reduction, this of course taking place in the respective halves of the gearbox. The rotation of gears 154 causes the rotation of respective outer shafts 150, each of which directly drives a small cam 146, as should now be apparent. The shaft 148 is directly coupled at each of its ends to one of the large cams 144, to cause the rotation thereof at a speed that is typically many times the speed of the small cams 146. For example, the large cams can turn nine times the speed of the small cams.

As already explained to some extent, and as further amplified with specific reference to FIGS. 9a through 90, the relative movement of image source 29 and macro lens by virtue of movement of their respective support plates 31 and 26 partially establishes the magnification of the desired visual images 106 and 108, although formation of these images is also affected by the position and movement of the macro lens 25 and image source 29 as a unit, relative to the fixed images 106 and 108. The latter positioning is of course brought about by means of the cams 144 and 146, with a pair of these cams being located on each side of the machine, as previously mentioned. Note FIGS. 3 through 8, wherein it is revealed with regard to each cam pair that cam 144 is the larger, outer cam, and cam 146 is the inner cam that is mounted in coaxial relation with the outer cam.

The basis for our using a pair of rotary cams on each side of the machine is that if we used a single cam operated at a uniform rate of speed, the grooves used therein in order that the desired ever-changing rate of lift could be obtained would either overlap, or else they would, at the other end of the cam, be so steep as to prevent the creation of lift.

Accordingly, we configure each inner cam 146 to have a groove 160 whose adjacent convolutions do not overlap. with this cam arranged to rotate comparatively slowly. The same groove, in effect, is continued as groove 1S8 disposed on the respective second cam 144, latter cam being disposed radially outwardly of the cam 146, and having a face disposed at the same level as the face of cam 146. Disposing the active faces of the cams in a coplanar relationship is accomplished by recessing the radially inner portion of the face of each cam 144 to receive the respective cam 146; note FIG. 5. Because of this arrangement, the cam follower fingers 156 on each side of the support plate 26 will be enabled to move smoothly from one groove to the other.

Each cam 144, as previously set forth, is caused to be rotated at a considerably faster rate of speed than cam 146, and this fact when coupled with the slope of the groove 158 established therein means that the support plate 26 will first be driven very slowly, then gradually faster. and then at the last, extremely fast. Significantly. our cam design enables smooth transition from very slow to very fast. accomplished from a constant speed drive.

Because the cams are driven in the same direction in a pre-established relationshsip by gears continuously in mesh. they periodically move into a rotative position such that in effect a continuous groove is defined as groove extremities 162 and 172 of grooves 160 and 158 respectively pass into a continuous relation. This of course makes it possible for fingers 156, while moving vertically. to pass easily and without interruption from one cam to the other. This transfer is accomplished due to the specific design and configuration of the openings at the groove extremities 162 and 172, as well as due to the maintenance of the proper rotative relationship of the cams.

It is quite necessary that the inner and outer cam pairs rotate at all times in the proper relationship to each other in order that the macro lens 25 and components related thereto will be moved in translation in the manner appropriate to the optical representation to be created. As already explained, it is an important facet of our invention that our compound cam arrangement causes a comparatively small amount of motion to be transmitted to the macro lens during one phase, and a much larger amount of motion to be transmitted to the macro lens during another phase.

In order that the outlet portion or extremity 162 of each inner cam groove 160-will be in the proper relationship with the inlet portions 172 of the groove 158 of the outer cams when the follower fingers 156 are to move between the cams of each respective pair, we at the time of manufacture of the cams cause appropriate alignment holes (not shown) to be placed therein. Then, during the setup of the machine, when the cams are being secured upon their respective mounting shafts, a pin is placed in each aligned pair of alignment holes, so as in effect to lock the cams together.

We usually align the cams with each other at the so called 1 to 1 point, that is, the locations in which the image source 29 is at its lowest point of travel, which is immediately prior to the time that the plate 26 is caused to move swiftly upward by the rapid rise portion 158' of the outer cams. Alignment also entails the placement of pins through other preestablished holes in the cams. and into appropriate holes in the ends of cam followers 156. This of course also locks the lens support plate 26 in a pre-established position with respect to the cam pairs.

The pinning of the cams to each other and the pinning of the followers 156 to the cams in the manner described assures that these portions of the drive mechanism of the machine are synchronized so that crossover of the followers 156 between the cams will be accomplished in the intended manner. This arrangement also makes it possible for the cam pairs on the opposite sides of the machine to be synchronized with each other so that the cam followers 156 on each side of the plate or table 26 will in fact pass from one cam of each pair of the other cam of each pair at the same time.

With the cams pinned and the cam followers pinned to the cams. we now are able to synchronize the threaded portions of the shafts 128 with the cams. At this time the gears 138 and 142 as well as the other portions of the gear train are locked together because of the aforementioned placement of the alignment pins in the cams, so appropriate rotative positioning of the shafts 128 can now take place. In order that this may be accomplished, we utilize bevel gears 138 constructed to have relatively movable splined hub portions. which can be locked in the desired positions with respect to the gear teeth by means of set screws (not shown). Thus, in order that alignment may be accomplished, we loosen these set screws, rotatively position the shafts 128 until image source 29 is in the correct position with respect to the macro lens and the images are the correct size, and then retighten the set screws so as to fix the hub and teeth portions of the gears 138, thus positioning the threaded portions 132 of the shafts I28 correctly with respect to the gear train.

With the cams still pinned together and to the follower fingers 156, and with the macro lens 25 in the l to l position, it is now possible to accurately focus the optics. This may be accomplished by placing a scale of known length in the location of 106 or 108 in FIG. 2. If this scale is for example eight-tenths of an inch long, an optical reproduction of this scale should appear at one image source 29, preferably upon a ground glass placed there for alignment purposes. Such optical reproduction or image on the ground glass should of course be the same length as the scale, or in this instance, 8/IO of an inch long. In the event the image length is not what it should be, we now can adjust the focus of macro lens 25, or further adjust the positions of the shafts 128 (with the set screws in gears 138 loosened) until such time as the scale is the same length in both locations.

Upon this being accomplished, the set screws can be tightened. This of course includes the set screws utilized in the gears 138, and those used in conjunction with the cams for the securing of same to their respective shafts in the correct orientation or relationship. Thereafter, the pins are of course to be removed from the cams.

Turning to FIG. 9, a schematic of optical elements of the RID is provided to further explain the relative positions and movement of the image source 29, macro lens 25, image I06 and collimating lens 94. As stated above, visual image 106 is maintained in a fixed position which has been predetermined based upon the focal point of collimating lens 94. As the positions between image source 29 and macro lens 25 change relative to each other and as a unit relative to the position of image 106, the visual image 106 and 108 comprise discrete portions of image source 29 magnified to various degrees. More specifically, in the subject embodiment of the RID, macro lens 25 is capable of a magnification demagnification range of I25 to l Of course, the precise rangeof magnification of macro lens 25 could be varied without changing the scope of the present invention. In the subject embodiment, however, it is important to note that macro lens 25 is capable of magnification demagnification from a microscopic to a telescopic range without physical inversion of the lens at the l to l magnification ratio position reached by the lens 25. This of course differs from conventional lens systems which introduce distortion if not inverted at this I to l magnification ratio.

FIG. 9a represents the largest portion of image source 29 to be viewed or projected through macro lens 25 which is at its maximum displacement from the positions of fixed image 106 or 108. The positions of the optical elements as shown in FIG. 9a define in image 106 and 108 a view of the largest target area seen by the optical scanner of the missile tracking system.

FIG. 912 discloses a l to l magnification ratio wherein macro lens 25 is closer to image source 29 but farther from the fixed positions of image 106 and 108 as compared to FIG. 9a. As stated above, a number of conventional lens systems need to be inverted at this point in order to provide magnification beyond the I to I ratio without distortion. In FIG. 9b a smaller portion of image source 29 is projected through macro lens 25 such that visual image 106 and 108 comprises a greater detailed view of a smaller portion of image source 29. FIG. discloses the largest magnification position of the present embodiment wherein macro lens 25 is clos est to image source 29 and furthest from the fixed positions of image 106 and 108. In this position, image 106 represents the most detailed, enlarged view of the smallest projected portion of the image source 29.

Assuming that image source 29 is a photographic form of a predetermined target area to be fed into the tracking system of missile 96 by means of optical tracker 97. FIG. 9a depicts image source 29 as being the largest ground area surrounding a given target point to be projected through macro lens 25 and to form image 106. This magnification occurs when follower finger 156 is at the inward extremity of groovoes portion 160 closest to the center of cam 146. FIG. 9c depicts the image source 29 as being the smallest ground area surrounding a given target point and further represents the greatest magnification of the target or impact point that can be practically transferred to the optical tracker 97 before impact occurs. With regard to the drive assembly, follower finger 156 will be positioned at the outer extremity of groove portion 158, farthest from the center of cam 144. FIG. 9b depicts an intermediate position wherein image source 29 represents a portion of the target area defining image source 106 which the optical tracker 97 secs at an intermediate altitude between impact and the maximum altitude at which the tracker views the target area.

Inasmuch as the alignment procedure was set forth in detail hereinabove, it will now be repeated. However, it should be pointed out that alignment starts with the positioning of RID l0 and missile 96. It is not required that the RID I0 or missile 96 be level. The missile 96 is first placed such that the lens 98 of missile 96 is in near proximity to projection lens 94. Thereafter, the light source 40 is activated. There is a location forward of the projection lens 94 which is the optimum location for the lens 98 to be placed; however, the accuracy requirements of this emplacement are usually not severe.

As shown in FIG. 10, the flux from the entire field of view of the image source 29 converges to a minimum size at a position slightly forward of lens 94, and then diverges. This location of minimum size is titled exit pupil 176. Since the lens 98 must receive all the light flux from the full field of view of the image source 29, it must be placed surrounding this converging and diverging flux. If lens 98 is of sufficient diameter, it may for instance be placed at ray position 174 and 174'. More specifically, the positioning of lens 98 of optical tracker 97 at the exit pupil 176 permits the use of a lens 98 having the smallest physical dimension.

It should be noted that at the start of the run, total flux is best utilized when the image source 29 is close to condenser lens 42 and is least efficient when image source 29 is close to lens 25 and furthest from condenser lens 42. Variable wedge 43 is therefore most overlapped at the start of the run when maximum light is available because of the lens geometry, and variable wedge 43 is least overlapped at the end of the run when total flux from light source 40 is least efficient. AI-

though distance between the bulb and the output lens is obviously a factor, it is comparatively minor when compared with that which is involved in the area of the transparency being worked with and uniformity of the collimating light beam. Near the beginning of the run almost the entire area of the transparency is being worked with, whereas near the end of the run only a small part of the transparency is being utilized.

[t is a design characteristic of this invention that, for a forward direction of operation, a constant rotational velocity of the motor 68 generates a change in image size at the optical tracker 97 of missile 96, which simulates a constant speed of approach of the sensor to the target. Now, since our forward direction of operation is that of approaching the target we have the range-totarget distance continually being reduced, or in one sense, going in a negative direction. Correspondingly, we will consider the change-in-image size in terms of demagnification,

m l/n =s'ls and where m is the magnification,

n is the demagnification,

s is the object-to-lens distance,

s is the lens-to-image distance, and

fis the effective focal length of the lens. Then,

Substituting and solving for s,

s'=s/n =f(p+ l)/n=f(l 1/11) Thus, the two equations defining the dimensions for object-to-lens distance and lens-to-image distance are:

Now, let us take derivatives of these two equations with respect to time and we obtain:

The term dn/dt is defining the rate-of-closure of range or distance to the target. The term ds/dl is the rate-of-change of the object-to-lens dimension, and the term ds'ldr is the rate-of-change of the lens-to-image dimension. We have thus found that the ds/d! (rate-ofchange of s) is directly proportional to dn/dl (rate-ofchange of the demagnification term, which is in turn directly proportional to the rate-of-change of range to target). To provide this direct proportionality, the object and lens are connected by a threaded member which is driven in constant rotation by a gear train extending to the motor 68. Such direct proportionality, provided by a constant-gearing assembly, provides a most convenient and useful method of simulating any desired constant speed of range closure, in that a constant speed motor can be utilized. This is to say, upon the desired speed setting being made, the motor 68 thereafter develops a constant speed in the gears, producing a constant rate of change in s, the uniformity required for simulating a constant-speed approach of a target.

Correspondingly, the ds'M! (rate-of-change of s) is proportional to f/n dnldt. This of course expresses the relationship of demagnification with respect to rate-of-change of .r'. This relationship is hyperbolic, for the ds'/dr is practically zero when n is large and it is practically infinite when n is mall. The zero control for s is provided by the nonlinear cams of our device.

As should now be apparent, for a constant speed of range closure, the cam system must separate the object and lens at an extremely slow rate at a time when n is large (when simulating a very large range to target) and must continuously increase that object-to-lens distance at an ever-increasing rate until it is extremely fast when n is small (when simulating a very small range to target).

The requirement thus has been to produce a nonlinear speed from very slow, then constantly increasing to very fast, from a constant speed setting of the motor; and to attain this nonlinear change of speed, we have of course provided the novel pair of double cams as described in detail hereinabove.

Although we obviously are not to be so limited, we have found that greater than percent of the time involved in the simulation of a typical range closure entails the use or operations of the small cams, with the large cams only coming into play in order to represent the final phase of the range closure, in which the macro lens is performing its magnification function. Inasmuch as a substantial movement of the lens is required during such magnification, prior art machines avoided trying to represent a range of magnification of from 40 to l, to say I20 to l, for cams able to move the lens properly during the initial phase, simply did not have the capability of providing the wide extent of motion needed for the final phase. The success enjoyed by our machine has to a large extent been made possible by our novel compound cam arrangement, wherein the curvature are sufficiently realistic as to easily move the table carrying the macro lens throughout all phases of the operation.

The operation of our novel autofocus enlarger coupled to a projector/collimator is further exemplified by FIG. 11, which basically is a graphical representation of the values 3 and s, but with this figure also containing what may be regarded as a summation of these values, represented of course by the uppermost curve, s s.

As will be recalled, the distance s represents the distance between the macro lens 25 and the image 108 (or 106), and this distance is substantially stationary when n is large. For example, in FIG. 11 it will be noted that as the demagnification unit n goes from a value of n 10 down to a value of n 2, the value of s', which is a distance, changes only very slightly. However, it will also be noted as n becomes progressively smaller, from n 2 down to n approaching 0, s increases at a very rapid rate, and this action is of course brought about by the aforementioned cams 146 and 144, which are directly responsible for generating the distance s'. More particularly, the almost straight line portion of the curve s represents for the most part the period that the cam follower 156 is interacting with the groove 160 of smaller cam 146, whereas the rapid rise portion of the curve .i" of course represents the interaction of the cam er 156 with the rapid rise portion 158' of large cam 144.

The dashed line in Flg. ll depicts the distance s, which is linearly proportional to n, with .i of course representing the distane between the macro lens 25 and the image source 29. Thus, as the threaded screw members 138 are caused to rotate at a constant rate, they continuously bring the macro lens and the image source closer together so as to decrease demagnification, which of course is increasing magnification.

The uppermost curve of FIG. 11 of course represents the summation of .s' s, or in other words represents the changing distance between the visual image 108 and the image source 29. As will be apparent, the threaded screw members 128 are in the first instance moving the image source 29 in the magnification increasing direction more rapidly than the small cam is moving the macro lens away from the visual image 108, with the effective speed ofthe threaded screw members and the cams becoming equal at a value of n 1. it will be noted that the curve s 5' becomes flat at the point where n l.

Thereafter, the effect of the cams becomes much more pronounced than the effect of the threaded screw members. and the distance between the image source and the visual image changes direction, and the increase of magnification becomes quite rapid at a time corresponding to the end of a range closure run.

We claim:

1. An optical device for providing a linearly expanding representation of a scene to simulate radical changes in range, comprising a mounting member, with respect to which an internal image of the scene can be formed, an enlarging lens mounted for extensive, nonlinear movements with respect to said member, a scene source mounted in optical relationship to said enlarging lens, and movable linearly with respect thereto, and means including a pair of cams, rotatable at different speeds about the same axis of rotation cooperating to provide motion between the scene source and said enlarging lens concurrently with providing motion between said enlarging lens and the internal image, such that because of preascertai optical relationships involving the characteristics of said enlarging lens, the location of the internal image will be essentially stationary with respect to said member, throughout a substantial size variation of the internal image.

2. The optical device as defined in claim 1 wherein said enlarging lens is a macro lens capable of substantially non-distorted magnification in both the microscopic and telescopic range without physical inversion of the lens.

3. The optical device as defined in claim 1 in which a second lens is utilized so as to place an image of said image source at a desired location outside said device.

4. The optical device as defined in claim 3 in which a substantially continuous image is formed throughout all operative relative positions of said image source, first lens and second lens.

5. The optical device as defined in claim 1 in which said pair of cams are utilized for providing motion between said enlarging lens and the internal image. and at least one threaded screw device. relatedly rotatable with said pair of cams, is used for providing motion between said scene source and enlarging lens.

6. An optical device for providing a linearly expanding representation of a scene to simulate radical changes in range, comprising a mounting member, with respect to which an internal image of the scene can be formed, an enlarging lens mounted for extensive. nonlinear movements with respect to said member, a scene source mounted in optical relationship to said enlarging lens, and movable linearly with respect thereto, and means for providing motion between the scene source and said enlarging lens concurrently with providing motion between said enlarging lens and the internal image, such that because of preascertained optical relationships involving the characteristics of said enlarging lens, the location of the internal image will be essentially stationary with respect to said member, throughout a substantial size variation of the internal image, said optical device also including additional lens means for projecting the internal image outside said mounting member for other optical purposes.

7. An optical device for providing a linearly expanding representation of a scene to simulate radical changes in range, comprising a mounting member. with respect to which an internal image of the scene can be formed. an enlarging lens mounted for extensive. nonlinear movements with respect to said member, a scene source mounted in optical relationship to said enlarging lens, and movable linearly with respect thereto, and means for providing motion between the scene source and said enlarging lens concurrently with providing motion between said enlarging lens and the internal image, such that because of preascertained optical relationships involving the characteristics of said enlarging lens, the location of the internal image will be essentially stationary with respect to said member, throughout a substantial size variation of the internal image, said optical device also including a second lens utilized so as to place an image of said image source at a desired location outside said device, as well as a tertiary lens system utilized for aligning the viewing direction of observing optics with the optical axis of said second lens.

8. An optical device for assuring proper focus of an image source over a wide range, so that extreme variations in distance to a location depicted on said image source can be rapidly and realistically represented, comprising an image source and supporting means therefor, a first lens and supporting means therefor, means for projecting said image source through said first lens so as to establish a substantially stationary internal image in said device, means for changing the distance between said first lens and said image source at a substantially uniform rate, means including a pair of cams, roatable at different speeds about a common axis of rotation, cooperating to cause mo ion of said first lens with respect to such internal image at an everchanging rate, with the image source being moved in accordance with a combined motion achieved by the contemporaneous operation of said distance changing means and said pair of cams.

9. The optical device as defined in claim 8 wherein said first lens is a macro lens capable of substantially non-distorted magnification in both the microscopic and telescopic range without physical inversion of the lens.

10. The optical device as defined in claim 8 in which a second lens is utilized so as to place an image of said image source at a desired location outside said device.

11. The optical device as defined in claim 19 in which a substantially continuous image is formed throughout all operative relative positions of said image source. first lens and second lens.

12. The optical device as defined in claim in which a tertiary lens system is utilized for aligning the viewing direction of observing optics with the image of the image source placed on the location outside the device.

13. The optical device as defined in claim 8 in which said pair of cams are utilized for providing motion between said enlarging lens and the internal image, and at least one threaded screw device, relatedly rotatable with said cams, is used to provide motion between said scene source and said enlarging lens.

14. A reference insertion device capable of receiving an image source and projecting same upon an observing optical arrangement, comprising an image source and means for supporting same, a first lens and means for movably supporting same with respect to said image source, while maintaining optical alignment therewith, means for providing motion between said image source and said first lens at a substantially constant rate, said first lens serving to form a primary internal image of a selected portion of the image source, means for providing relative motion at an ever-changing rate between said first lens and the primary internal image latter means including a pair of cooperating cams rotatable at different speeds about a common axis of rotation, the relative motion occurring between said image source and the primary internal image thus being a combination of motions, which result in the controlled simulation of rapid range change, and a second lens serving as an output lens for the device and arranged to direct light representative of said primary internal image onto a location outside the device.

15. The device as defined in claim 14 in which said first lens is a macro lens capable of substantially nondistorted magnification in both the microscopic and telescopic range without physical inversion of the lens.

16. The device as dfined in claim 14 in which said range change is in the direction of range closure.

17. A reference insertion device capable of receiving an image source and projecting same upon an observing optical arrangement, comprising an image source and means for supporting same, a first lens and means for movably supporting same with respect to said image source, while maintaining optical alignment therewith, means for providing motion between said image source and said first lens at a substantially constant rate, said first lens serving to form a primary internal image of a selected portion of the image source, a second lens serving as an output lens for the device and arranged to direct light representative of said primary internal image onto a location outside the device, means for providing relative motion between said first lens and said output lens, which motion is at an ever-changing rate, the relative motion occurring between said image source and said output lens thus being a combination of motions, which result in the controlled simulation of rapid range change, and a secondary optical path involving the use of a lens arrangement arranged to observe a secondary internal image originating from said image source, and means associated with latter lens arrangement for superimposing an illuminated mark upon such secondary internal image, said mark being usable in aligning the image source such that a certain location on the image source can be designated to be projected along the optical axis of said second lens.

18. The device as defined in claim 17 in which means associated with said secondary optical path serves to place an image of said illuminated mark to be projected into a tertiary optical path, said image becoming a ref' erence for viewing and aligning the observing optics disposed at a location outside the device, such that said observing optics will be pointed toward the optical axis of said second lens.

19. The reference insertion device as defined in claim 18 in which said observing optics have an illuminated focal phase having a critical center element, said refer ence insertion deivce having a tertiary optical path utilized for aligning the image projected outside the device onto such observing optics, said tertiary arrangement functioning to make it possible to view the illuminated mark as if superimposed upon said critical element, such alignment being completed when the image of the critical center element of the focal plane of the observing optics in the primary internal image location appears to be superimposed on the image of the illuminated mark in the secondary image location,

20. A reference insertion device for providing an image of a target scene over a wide range of magnification in order to represent range closure, comprising a movable illuminated image source, means for supporting a first lens in alignment with said source such that light can be passed through said lens and thus create an internal image in said device, and a second lens for projecting the internal image from said image source onto a location outside the device, means for providing essentially constant relative motion between said image source and said first lens, means for supplying nonlinear motion betweeen said means for supporting said first lens and said second lens, with the speed of latter relative motion increasing rapidly with the elapse of time, whereby a substantially stationary internal image is provided for said second lens to project, but the projected image represents a considerable change in magnification of at least a portion of said image source, such nonlinear motion being supplied to said first lens support means by at least one pair of earns, a radially inner cam and a radially outer cam, each of which is rotatable about the same axis of rotation but at different speeds, each of said earns having a surface adapted to be contacted by cam follower means disposed upon said first lens support means, said cam follower means contacting first the radially inner cam and then the radially outer cam, with latter cam having a surface which, with cam rotation, rapidly moves away from said axis of rotation in a nonlinear manner, with the result that said cam follower means and hence said first lens support means is caused to move rapidly away from said second lens, with the speed of travel of said first lens support means being at an ever increasing rate with respect to said second lens.

21. A reference insertion device for providing an image of a targer scene over a wide range of magnification in order to represent range closure, comprising a movable illuminated image source, means for supporting a first lens in alignment with said source such that light can be passed through said lens and thus create an internal image in said device, and a second lens for projecting the internal image from said image source onto a location outside the device, means for providing essentially constant relative motion between said image source and said first lens, means for supplying nonlinear motion between said means for supporting said first lens. and said second lens, with the speed of latter relative motion increasing rapidly with the elapse of time, whereby a substantially stationary internal image is provided for said second lens to project, but the projected image represents a considerable change in magnification of at least a portion of said image source, said device further including means for selecting which portion of such target scene is projected outside the device.

22. The device in claim 21 in which means are provided for aligning the selected portion with receiving optics disposed at a point of use outside the device.

23. An optical device for providing a linearly expanding represention of a scene to simulate radical changes in range comprising a mounting member, with respect to which an internal image of the scene can be maintained, an enlarging lens disposed on a supporting plate for extensive, nonlinear movements with respect to said mounting member, a scene source mounted in optical relationship to said enlarging lens and movable linearly with respect thereto, and means for providing motion between said scene source and said enlarging lens concurrently with providing motion between said enlarging lens and the internal image. thereby to cause the location of the internal image to remain essentially stationary. said motion providing means including a compound cam arrangement, and a cam follower utilized therewith; said cam follower being mounted in a relatively fixed position with respect to said supporting plate, said compound cam arrangement involving an inner cam and an outer cam, each rotatable about the same axis of rotation but at different relative speeds, said cams having active faces that are substantially c0- planar, in each of which faces a cam groove in the form of a spiral of preestablished configuration is disposed, the rotative relationships of said cams being such that said cam follower can move from the groove of one of said cams to the groove of the other of said cams at a preascertained rotative relationship of the cams, thereby making possible a much wider range of motion of said enlarging lens then would be possible if utilizing only a single cam.

24. The optical defice as defined in claim 23 in which said compound cam arrangement is utilized to provide motion between said enlarging lens and the internal image, and at least one threaded screw device is used to provide motion between said scene source and said enlarging lens. 

1. An optical device for providing a linearly expanding representation of a scene to simulate radical changes in range, comprising a mounting member, with respect to which an internal image of the scene can be formed, an enlarging lens mounted for extensive, nonlinear movements with respect to said member, a scene source mounted in optical relationship to said enlarging lens, and movable linearly with respect thereto, and means including a pair of cams, rotatable at different speeds about the same axis of rotation cooperating to provide motion between the scene source and said enlarging lens concurrently with providing motion between said enlarging lens and the internal image, such that because of preascertai optical relationships involving the characteristics of said enlarging lens, the location of the internal image will be essentially stationary with respect to said member, throughout a substantial size variation of the internal image.
 2. The optical device as defined in claim 1 wherein said enlarging lens is a macro lens capable of substantially non-distorted magnification in both the microscopic and telescopic range without physical inversion of the lens.
 3. The optical device as defined in claim 1 in which a second lens is utilized so as to place an image of said image source at a desired location outside said device.
 4. The optical device as defined in claim 3 in which a substantially continuous image is formed throughout all operative relative positions of said image source, first lens and second lens.
 5. The optical device as defined in claim 1 in which said pair of cams are utilized for providing motion between said enlarging lens and the internal image, and at least one threaded screw device, relatedly rotatable with said pair of cams, is useD for providing motion between said scene source and enlarging lens.
 6. An optical device for providing a linearly expanding representation of a scene to simulate radical changes in range, comprising a mounting member, with respect to which an internal image of the scene can be formed, an enlarging lens mounted for extensive, nonlinear movements with respect to said member, a scene source mounted in optical relationship to said enlarging lens, and movable linearly with respect thereto, and means for providing motion between the scene source and said enlarging lens concurrently with providing motion between said enlarging lens and the internal image, such that because of preascertained optical relationships involving the characteristics of said enlarging lens, the location of the internal image will be essentially stationary with respect to said member, throughout a substantial size variation of the internal image, said optical device also including additional lens means for projecting the internal image outside said mounting member for other optical purposes.
 7. An optical device for providing a linearly expanding representation of a scene to simulate radical changes in range, comprising a mounting member, with respect to which an internal image of the scene can be formed, an enlarging lens mounted for extensive, nonlinear movements with respect to said member, a scene source mounted in optical relationship to said enlarging lens, and movable linearly with respect thereto, and means for providing motion between the scene source and said enlarging lens concurrently with providing motion between said enlarging lens and the internal image, such that because of preascertained optical relationships involving the characteristics of said enlarging lens, the location of the internal image will be essentially stationary with respect to said member, throughout a substantial size variation of the internal image, said optical device also including a second lens utilized so as to place an image of said image source at a desired location outside said device, as well as a tertiary lens system utilized for aligning the viewing direction of observing optics with the optical axis of said second lens.
 8. An optical device for assuring proper focus of an image source over a wide range, so that extreme variations in distance to a location depicted on said image source can be rapidly and realistically represented, comprising an image source and supporting means therefor, a first lens and supporting means therefor, means for projecting said image source through said first lens so as to establish a substantially stationary internal image in said device, means for changing the distance between said first lens and said image source at a substantially uniform rate, means including a pair of cams, roatable at different speeds about a common axis of rotation, cooperating to cause motion of said first lens with respect to such internal image at an ever-changing rate, with the image source being moved in accordance with a combined motion achieved by the contemporaneous operation of said distance changing means and said pair of cams.
 9. The optical device as defined in claim 8 wherein said first lens is a macro lens capable of substantially non-distorted magnification in both the microscopic and telescopic range without physical inversion of the lens.
 10. The optical device as defined in claim 8 in which a second lens is utilized so as to place an image of said image source at a desired location outside said device.
 11. The optical device as defined in claim 19 in which a substantially continuous image is formed throughout all operative relative positions of said image source, first lens and second lens.
 12. The optical device as defined in claim 10 in which a tertiary lens system is utilized for aligning the viewing direction of observing optics with the image of the image source placed on the location outside the device.
 13. The optical device as defined in claim 8 in which said pAir of cams are utilized for providing motion between said enlarging lens and the internal image, and at least one threaded screw device, relatedly rotatable with said cams, is used to provide motion between said scene source and said enlarging lens.
 14. A reference insertion device capable of receiving an image source and projecting same upon an observing optical arrangement, comprising an image source and means for supporting same, a first lens and means for movably supporting same with respect to said image source, while maintaining optical alignment therewith, means for providing motion between said image source and said first lens at a substantially constant rate, said first lens serving to form a primary internal image of a selected portion of the image source, means for providing relative motion at an ever-changing rate between said first lens and the primary internal image latter means including a pair of cooperating cams rotatable at different speeds about a common axis of rotation, the relative motion occurring between said image source and the primary internal image thus being a combination of motions, which result in the controlled simulation of rapid range change, and a second lens serving as an output lens for the device and arranged to direct light representative of said primary internal image onto a location outside the device.
 15. The device as defined in claim 14 in which said first lens is a macro lens capable of substantially non-distorted magnification in both the microscopic and telescopic range without physical inversion of the lens.
 16. The device as dfined in claim 14 in which said range change is in the direction of range closure.
 17. A reference insertion device capable of receiving an image source and projecting same upon an observing optical arrangement, comprising an image source and means for supporting same, a first lens and means for movably supporting same with respect to said image source, while maintaining optical alignment therewith, means for providing motion between said image source and said first lens at a substantially constant rate, said first lens serving to form a primary internal image of a selected portion of the image source, a second lens serving as an output lens for the device and arranged to direct light representative of said primary internal image onto a location outside the device, means for providing relative motion between said first lens and said output lens, which motion is at an ever-changing rate, the relative motion occurring between said image source and said output lens thus being a combination of motions, which result in the controlled simulation of rapid range change, and a secondary optical path involving the use of a lens arrangement arranged to observe a secondary internal image originating from said image source, and means associated with latter lens arrangement for superimposing an illuminated mark upon such secondary internal image, said mark being usable in aligning the image source such that a certain location on the image source can be designated to be projected along the optical axis of said second lens.
 18. The device as defined in claim 17 in which means associated with said secondary optical path serves to place an image of said illuminated mark to be projected into a tertiary optical path, said image becoming a reference for viewing and aligning the observing optics disposed at a location outside the device, such that said observing optics will be pointed toward the optical axis of said second lens.
 19. The reference insertion device as defined in claim 18 in which said observing optics have an illuminated focal phase having a critical center element, said reference insertion deivce having a tertiary optical path utilized for aligning the image projected outside the device onto such observing optics, said tertiary arrangement functioning to make it possible to view the illuminated mark as if superimposed upon said critical element, such alignment being completed when the image of the cRitical center element of the focal plane of the observing optics in the primary internal image location appears to be superimposed on the image of the illuminated mark in the secondary image location.
 20. A reference insertion device for providing an image of a target scene over a wide range of magnification in order to represent range closure, comprising a movable illuminated image source, means for supporting a first lens in alignment with said source such that light can be passed through said lens and thus create an internal image in said device, and a second lens for projecting the internal image from said image source onto a location outside the device, means for providing essentially constant relative motion between said image source and said first lens, means for supplying nonlinear motion betweeen said means for supporting said first lens and said second lens, with the speed of latter relative motion increasing rapidly with the elapse of time, whereby a substantially stationary internal image is provided for said second lens to project, but the projected image represents a considerable change in magnification of at least a portion of said image source, such nonlinear motion being supplied to said first lens support means by at least one pair of cams, a radially inner cam and a radially outer cam, each of which is rotatable about the same axis of rotation but at different speeds, each of said cams having a surface adapted to be contacted by cam follower means disposed upon said first lens support means, said cam follower means contacting first the radially inner cam and then the radially outer cam, with latter cam having a surface which, with cam rotation, rapidly moves away from said axis of rotation in a nonlinear manner, with the result that said cam follower means and hence said first lens support means is caused to move rapidly away from said second lens, with the speed of travel of said first lens support means being at an ever increasing rate with respect to said second lens.
 21. A reference insertion device for providing an image of a targer scene over a wide range of magnification in order to represent range closure, comprising a movable illuminated image source, means for supporting a first lens in alignment with said source such that light can be passed through said lens and thus create an internal image in said device, and a second lens for projecting the internal image from said image source onto a location outside the device, means for providing essentially constant relative motion between said image source and said first lens, means for supplying nonlinear motion between said means for supporting said first lens, and said second lens, with the speed of latter relative motion increasing rapidly with the elapse of time, whereby a substantially stationary internal image is provided for said second lens to project, but the projected image represents a considerable change in magnification of at least a portion of said image source, said device further including means for selecting which portion of such target scene is projected outside the device.
 22. The device in claim 21 in which means are provided for aligning the selected portion with receiving optics disposed at a point of use outside the device.
 23. An optical device for providing a linearly expanding represention of a scene to simulate radical changes in range comprising a mounting member, with respect to which an internal image of the scene can be maintained, an enlarging lens disposed on a supporting plate for extensive, nonlinear movements with respect to said mounting member, a scene source mounted in optical relationship to said enlarging lens and movable linearly with respect thereto, and means for providing motion between said scene source and said enlarging lens concurrently with providing motion between said enlarging lens and the internal image, thereby to cause the location of the internal image to remain essentially stationary, said motion providing means including a compound cam arrangement, and a cam follower utilized therewith; said cam follower being mounted in a relatively fixed position with respect to said supporting plate, said compound cam arrangement involving an inner cam and an outer cam, each rotatable about the same axis of rotation but at different relative speeds, said cams having active faces that are substantially coplanar, in each of which faces a cam groove in the form of a spiral of preestablished configuration is disposed, the rotative relationships of said cams being such that said cam follower can move from the groove of one of said cams to the groove of the other of said cams at a preascertained rotative relationship of the cams, thereby making possible a much wider range of motion of said enlarging lens then would be possible if utilizing only a single cam.
 24. The optical defice as defined in claim 23 in which said compound cam arrangement is utilized to provide motion between said enlarging lens and the internal image, and at least one threaded screw device is used to provide motion between said scene source and said enlarging lens. 